Articles: closed-circuit-anesthesia.
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To determine the concentrations of sevoflurane and compound A (a degradation product of sevoflurane) in the anesthetic circuit when sevoflurane was delivered with an in-circuit vaporizer, and to determine the cardiorespiratory effects of sevoflurane in dogs. ⋯ Results suggested that sevoflurane can be administered to nonsurgically stimulated dogs, using an in-circuit vaporizer and low (< 15 ml/kg/min) oxygen flow rates, without causing significant cardiorespiratory depression or clinically important concentrations of compound A.
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Anaesth Intensive Care · Apr 1998
Comparative StudyAnaesthesia circuits, humidity output, and mucociliary structure and function.
We compared the effects of humidity delivered by the circle system at low fresh gas flows (FGF) with a conventional two-limb and coaxial circuit on the structure and function of the tracheobronchial epithelium in dogs. Animals were anaesthetized and mechanically ventilated using an anaesthesia ventilator to maintain normocarbia. Group I (control) animals received a FGF equal to the required minute ventilation mimicking an open circuit technique. ⋯ Alterations in tracheobronchial structure and function result from exposure to dry gases and are amplified by the duration of exposure. Our findings suggest a minimum of 12 to 15 mg H2O/l is necessary to prevent these alterations. In this study, the combination of low FGF and a coaxial anaesthesia circuit reached this minimum threshold more quickly than a conventional two-limb circuit.
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J Clin Monit Comput · Feb 1998
Comparative StudyMethane influences infrared technique anesthetic agent monitors.
During closed-circuit anesthesia, anesthetic vapor analysis by infrared absorption at 3.3 microm can be influenced by the concentration of accumulated methane, resulting in inaccurate readings of anesthetic concentrations. The current study examined the influence of different known methane concentrations on the analysis of halothane or isoflurane concentrations by the infrared absorption technique. ⋯ In closed circuit or low-flow anesthesia, in which methane can accumulate, infrared measuring techniques for potent inhalation anesthetics that do not use the 3.3 microm wavelength appear to be preferable.
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Paediatric anaesthesia · Jan 1998
Comparative Study Clinical TrialSafety and efficacy of semi-closed circle ventilation in small infants.
The purpose of this clinical trial was to investigate the safety and efficacy of semi-closed circle ventilation of the Dräger anaesthesia ventilators (Cicero, Cato), using a fresh gas flow (FGF) of 600 ml.min-1. Twenty infants, weighing less than 6000 g, without cardiorespiratory abnormalities who required general anaesthesia of at least 30 min were included. The FGF was reduced to 600 ml.min-1 after 10 min of denitrogenation with a FGF of 4 to 61.min-1. ⋯ Hypoxic gas concentrations were not observed. Neither nitrogen nor CO2 accumulated in the circle system. In conclusion, low flow anaesthesia can be performed safely in infants under 6000 grams with the Dräger Cicero and Cato anaesthesia ventilators.